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3 years ago

What property do all of the group 18 elements have that make them stand out from other elements?

1 answer:

5 0

They are very stable (not reactive).

This is because their outer shell has a total of 8 valence electrons. All elements strive to get towards a full outer shell, but since these elements already have a full outer shell, they are fairly unreactive.

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Attempt 3 An irregular lump of an unknown metal has a measured density of 5.50 g/mL. The metal is heated to a temperature of 153

shepuryov [24]

Answer:

i think it's 20.0mL

Explanation:

i learned this question in class

4 0

3 years ago

How many moles are in 7.6 g of Ca

klasskru [66]

Your answer would be 0.024951344877489 but rounding it would be 0.025 moles

7 0

3 years ago

At room temperature (20°C} and pressure, the density of air is 1.189 g/L. An object will float in air if its density is less tha

Alekssandra [29.7K]

Explanation:

$Density =\frac{Mass}[Volume}$

Density of the air ,d= 1.189 g/L

(a) Density of the evacuated ball

Mass of the ball ,m = 0.12 g

Volume of the ball = $V=560 cm^3=560 ml=0.560 L$

$D =\frac{0.12 g}{0.560 L}=0.214 g/L$

D<d, teh evacuated ball will flaot in air.

(b) Density of the evacuated ball D = 0.214 g/L

Density of carbon dioxide gas = $d_1=1.830 g/L$

Mass of the carbon dioxide gas :

$1.830 g/L\times 0.560 L=1.0248 g$

Total density of filled ball with carbon dioxide gas:

$\frac{0.12 g+1.0248 g}{0.560 L}==2.044 g/L$

The ball filled with carbon dioxide will not float in the air because total density of filled ball is greater than the density of an air.

(c) Density of the evacuated ball D = 0.214 g/L

Density of hydrogen gas = $d_2=0.0899 g/L$

Mass of the hydrogen gas :

$1.830 g/L\times 0.560 L=0.050344 g$

Total density of filled ball with hydrogen gas:

$\frac{0.12 g+0.050344 g}{0.560 L}==0.3041 g/L$

The ball filled with hydrogen will float in the air because total density of filled ball is lessor than the density of an air.

(d) Density of the evacuated ball D = 0.214 g/L

Density of oxygen gas = $d_3=1.330 g/L$

Mass of the oxygen gas :

$1.330 g/L\times 0.560 L=1.7448 g$

Total density of filled ball with oxygen gas:

$\frac{0.12 g+1.7448 g}{0.560 L}=1.5442 g/L$

The ball filled with oxygen will not float in the air because total density of filled ball is greater than the density of an air.

(e) Density of the evacuated ball D = 0.214 g/L

Density of nitrogen gas = $d_4=1.165 g/L$

Mass of the nitrogen gas :

$1.165 g/L\times 0.560 L=0.6524 g$

Total density of filled ball with nitrogen gas:

$\frac{0.12 g+0.6524 g}{0.560 L}==1.3792 g/L$

The ball filled with nitrogen will not float in the air because total density of filled ball is greater than the density of an air.

f) Mass must be added to sink the ball = m

Density of ball > Density of the air ; to sink the ball.

$\frac{0.12g +m}{0.560L}>1.189 g/L$

m > 0.54584 g

For any case weight added to ball to make it sink in an air should be grater than the value of 0.54584 grams.

5 0

3 years ago

Inclined planes reduce the amount of effort needed to move an object, but increases

QveST [7]

Inclined planes reduce the amount of effort needed to move an object, but increases the length of the ramp.

<u>Explanation:</u>

Mechanical advantage is the measure of amount of effort needed to move an object. The mechanical advantage can be calculated as the ratio of length of ramp to the height of ramp for an inclined plane.

As it is known that an object can be easily moved on an inclined plane than on a vertical plane, this is because, the inclined plane provides greater output force. But in that case, the effort required will be reduced with the cost of increasing the distance of the movement of object.

In other terms , the ramp's length of inclined planes has to get increased in order to reduce the amount of effort needed to move an object. This is because as the mechanical advantage has length of the ramp in the numerator, with the increase in numerator value or length value the mechanical advantage will also increase.

8 0

3 years ago

There have been different models of the atom over time. How has the competition between these models affected our understanding

lions [1.4K]

Doing the same final thanks

6 0

3 years ago

Read 2 more answers